A one-year, controlled study of the effect of adding naltrexone to drug-free, recovery-oriented treatment of narcotic dependency is proposed. Sixty patients hospitalized for treatment of narcotic dependency at Merritt Peralta Chemical Dependency Recovery Hospital (a private, not-for-profit hospital in Oakland, CA), who give informed consent to participate in the study, will be randomly assigned to either a control group (30 subjects who, after discharge from the hospital, receive all program aftercare services plus twice-weekly urine testing) or the naltrexone group (30 subjects who, after discharge from the hospital, will receive all program aftercare services plus twice-weekly, nurse-administered doses of naltrexone). The two groups will receive the same amount of staff contact and will receive identical aftercare services during the one year study. Subjects will be comprehensively assessed while inpatient and 3, 6, 9 and 12 months after discharge. Outcome measures are: results of urine screens (for opiates and other drugs of abuse), participation in aftercare group, retention time in treatment group, and psychosocial measures. Multivariate, between-group analysis will be used to determine the effect of adding naltrexone to recovery-oriented treatment. Discriminant analysis will be used to identify predictor variables which forecast successful or unsuccessful naltrexone treatment group outcome.